"The data presented reveal that damage in PsA is associated with irreversible disability as in rheumatoid arthritis (RA) and that the major culprit in this respect is cartilage destruction," Aletaha and colleagues wrote. "This implies that prevention of joint damage and especially preservation of cartilage structure is of particular importance and, therefore, would support the claim to diagnose and treat PsA rapidly and effectively, as well as the currently accepted treatment targets of remission of disease activity."

The original study -- fully titled Golimumab: A Randomized Evaluation of Safety and Efficacy in Subjects with Psoriatic Arthritis Using a Humanized Anti-TNF Monoclonal Antibody -- evaluated the drug against placebo. Researchers obtained Modified Sharp/van der Heijde Scores (mSvdHS) from 363 of the original 405 patients to assess structural damage, which was quantified at baseline and after 24, 52 and 104 weeks. The mSvdHS is based on scoring of erosions and joint space narrowing, with a maximum score of 320 for erosions and 208 for joint space narrowing, resulting in an mSvdHS ranging from 0 to 528.

Researchers used the Disease Activity Index for Psoriatic Arthritis (DAPSA) for disease activity assessment, and they used the Health Assessment Questionnaire (HAQ) disability index to associate disease activity and functional status.

Overall, they found that structural damage was tied to functional disability, independent of disease activity.

The effect of structural damage on function was significant in disease activity-adjusted models using total mSvdHS (P=0.005). Analyses of subscores showed that the effect was mainly related to the effects of joint space narrowing (P=0.001) and, to a lesser extent, to the effects of erosions (P=0.019).

Because joint space narrowing was more strongly associated with functional impairment than erosions, "a focus on preserving joint integrity can be called on, with a specific consideration of joint space narrowing in radiographic assessment," the researchers wrote.

The association between disability and joint damage was particularly prominent in patients who were in clinical remission and whose physical function was not affected by disease activity. A patient in remission using DAPSA criteria with an mSvdHS of 10, 50, 100, or 150 would have a predicted residual mean HAQ of 0.02, 0.1, 0.2 and 0.3, respectively, the researchers reported.

"As the minimally clinical important difference of the HAQ in PsA lies between 0.3 and 0.35, patients with long-standing PsA and/or substantial radiographic damage would experience a clinically meaningful irreversible change of physical function," they wrote.

When mSvdHS scores were separated into tertiles, the potential to achieve a normal HAQ was reduced markedly for those in the highest tertile of damage compared with the lowest (RR 0.58, 95% CI 0.35-0.96, P=0.029).

Functional responsiveness was found to be impaired in patients with structural damage: among DAPSA major responders, the change in HAQ scores decreased significantly with increasing levels of overall structural damage (P=0.01 for total mSvdHS and P=0.013 for absolute or relative change in HAQ).

The authors asserted that "the claim can be made that structural changes in PsA are not mere epiphenomena of the disease, but clearly relate to physical functioning and overall health status of these patients."

They also noted several limitations, including the lack of data available on comorbidities; the potential effect of nonpharmacologic treatment on physical function, which could not be measured; the limitations of the mSvdHS, which doesn't take into account axial skeletal involvement or bony proliferation; and the low degrees of structural damage in the patients enrolled in GO-REVEAL.

"Our results reveal that responsiveness of functional limitations decreases with increasing joint damage," Aletaha and colleagues concluded. "They further suggest that -- similar to what has been shown in RA -- joint space narrowing is functionally more important than erosions."

Accessibility Statement

At MedPage Today, we are committed to ensuring that individuals with disabilities can access all of the content offered by MedPage Today through our website and other properties. If you are having trouble accessing www.medpagetoday.com, MedPageToday's mobile apps, please email legal@ziffdavis.com for assistance. Please put "ADA Inquiry" in the subject line of your email.